Showing papers in "Plant Physiology in 1944"

Relation between light intensity and rate of photosynthesis of loblolly pine and certain hardwoods.

Abstract: One of the most important forestry problems in the south concerns the tendency of pine stands to be succeeded by hardwoods. This occurs because pine seedlings usually fail to survive under forest canopies while the seedlings of many hardwood species survive and grow. It is often supposed that the failure of pine seedlings to grow under a forest canopy results from their high light requirements. Pine seedlings are assumed to be unable to carry on photosynthesis rapidly enough in the shade of a forest canopy to survive. Many hardwoods which presumably have lower light requirements and can therefore manufacture food more efficiently in the shade are able to grow" vigorously under these conditions. Experiments of Korstian and Coile (?) indicate, however, that pine seedlings will thrive in the shade of a pine or hardwood stand if protected from the root competition of the over-story trees by trenching. Evidently pine seedlings can carry on enough photosynthesis in the shade to provide food for growth, if supplied with sufficient water.

Effects of oxygen tension on certain physiological responses of rice, barley, and tomato.

Abstract: The relation of oxygen pressure to some metabolic processes of plants has been examined in recent experimental work with particular reference to the energy requirements of active cells. The reactions studied under the most carefully controlled conditions are accumulation of salt and respiration by excised roots and storage organs. This is particularly true of the work by Hoagland and his associates at the University of California, and Steward at the University of London. Other investigations have been concerned with the response of entire plants to oxygen deficiency in the roots. Earlier studies compared plants grown in submerged soils with those grown in well-drained soils. It is evident that the control over such experiments is complicated by the influence of several variables such as carbon dioxide pressure, accumulation of anaerobic products, and the intervention of microbiological activity. Greater control has been possible when water cultures have been employed, exposing the root systems to continuous streams of air or relatively pure nitrogen. The influence of oxygen supply on tomato, buckwheat, barley, lupine, and other plants has been studied in this way. The oxygen relations of the rice plant present a particularly interesting and important problem since as a crop it is grown under conditions (apparently anaerobic) which inhibit the growth of many field plants. This ability of rice to thrive in submerged soil has been observed and confirmed by some research workers and denied by others. A rather large number of diverse experiments on a qualitative scale has left suspended a final estimation of the capacity of rice, real or apparent, to grow in an anaerobic root environment.

Mycorrhizal symbiosis in aplectrum, corallorhiza and pinus.

Abstract: When plants of different types are closely crowded together or anatomically engaged, in addition to the ensuing competitions, several special relations including immunities, antagonisms, toxicities, parasitism, or symbiosis may arise. A secretion by one plant which inhibits the growth of a neighboring organism, such as the substance found in the tissues of orchids by NOEL BERNARD which limits the growth of the hyphae of endophytic fungi, results in an immunity. Similar antagonisms exist between some fungi growing together in the soil in which a secretion from one limits the growth of the other (11). This constructively defense mechanism varies widely. In one instance described by STOLLER (21) Psalliota campestris produces a diffusible oxidizing substance, acting as a quinone which protects the mushroom against microorganisms producing sulphides. The action of the \" humoral \" secretion in such cases is to be distinguished from toxicity by the fact that in the first case the secretion simply blocks some of the processes of cell-metabolism but does not destroy the mechanism; in toxic action a theoretical secretion causes irreversible and fatal changes in the cytochemical set-up of living cells of the organism affected. In parasitism, in addition to possible anatomical and cytochemical damage, a fatal extraction of nutritive material may ensue. Further distinction between parasitism and symbiosis will be made in the following pages. A much heightened interest in the bacteriostatic secretions of molds, of which penicillin is the most notable because of its sterilizing action in surgery, now prevails. This secretion specifically inhibits the growth of grampositive bacteria but does not destroy them; secretions such as patulin exert similar. action on both gram-positive and gram-negative bacteria [see also BURGESS (2)]. Scope of the present paper

A study of the sulphur metabolism of wheat, barley and corn using radioactive sulphur.

Abstract: Radioactive sulphur (S35) with its weak beta radiation of 0.120 M.E.V. and its long half-life of 87 to 88 days (6, 8) has desirable characteristics as a biological tracer, particularly since its activity can be readily measured after recovery as barium sulphate (6). Further, as will be shown in the following paper (5), excellent autographs of thin sections of plant material can be made on photographic film. Seaborg (9) and Hamilton (3, 4) have reviewed the literature up to 1941 on the use of radioactive elements as tracers in chemical and biological work. Radiosulphur in synthetic cystine, methionine, and thiamin as well as inorganic compounds, has been used in nutritional studies of animals (1,10), but so far as is known, nutritional studies of plants using radiosulphur have not been reported. This paper describes experiments carried out in 1942 with radiosulphur furnished as barium sulphate*2 by Dr. J. G. Hamilton of the Radiation Laboratory, University of California. The sulphur* was added to vegetation growing in the large sand cultures (13) both as a soluble sulphate* in the nutrient solution and as sulphur* dioxide in the air. No radiosulphur was available during the 1943 season.

Effect of nutrient ratio and concentration on growth and composition of tomato plants and on the occurence of blossom-end rot of the fruit

Abstract: Much work has been done on physiological balance where from two to six major elements have been varied, with the osmotic concentration nearly constant. In this experiment only one major element was. varied in the ratio, but no attention was paid to the osmotic concentration. This would be more nearly like the application of fertilizer under field conditions. Blossom-end rot has recently been reviewed by Robbins (2) with many references given on the subject. In most cases a disturbance of the normal water relations has been assigned as a cause of the physiological disease. This experiment was set up to study the effect of balance of nutrient elements on the growth of tomato plants grown in sand culture using the subirrigation method. Materials and methods

Apparent photosynthesis in some conifers during winter

Abstract: Since the appearance of a paper by Jumelle (4) on the effect of low temperatures upon " assimilation/9 there have been a number of publications dealing with this subject. The chief points of interest seem to have been in locating the maximal and minimal temperatures for photosynthesis and respiration and in plotting the course or rates of these processes with respect to variations in temperature. Jumelle placed the plant material, such as spruce branches and lichens, in apparatus where temperature and light could be varied and attempted to measure changes in the composition of the surrounding air. From his results he concluded that spruce and lichens could carry on "assimilation" at temperatures as low as -30? C. and -40? C, respectively, and that "assimilation* ' continued at a much lower temperature than did respiration. His results have been questioned and his methods adversely criticized by subsequent workers. E wart (1) reported that many plants, including Pinus montana, Taxus baccata, Thuja occidentalis, and Juniperus sabina, following three weeks of January weather often as cold as -15? C. were unable to carry on "assimilation" even when exposed to a temperature as high as 15? C. until after a lapse of from 2 to 8 hours of time. Furthermore, respiration was found to be active at temperatures too low for " assimilation, ' ' and after plants had been exposed to low temperatures and subsequently to warm temperatures respiration became apparent before i i assimilation. ' ' Matthaei (5, 6) also questioned the work of Jumelle. She was able to detect "assimilation" in a detached cherry laurel leaf at 6? C, and agreed with Ewart that respiration occurred at lower temperatures than did "assimilation."

Relation of light to growth of plants

Abstract: Plants grown in varying intensities of light from full sun to darkness show characteristic and well-known differences in growth and development. Much of this effect is frequently summed up in the phrase, \"light retards growth,\" which has become almost axiomatic in plant physiology and has been used to explain certain types of phototropism as well as the varying growth rates of etiolated and unetiolated plants, etc. Like many other physiological axioms, the inhibiting effect of light was popularized by SACHS (20) who performed some of the early experiments indicating that plants may make most of their growth in darkness. SACHS recognized the several secondary effects of light on growth, but thought it directly inhibiting through some action on the growing regions. Numerous other workers have considered light inhibiting for growth. PRANTL (18), POPP (15) and McCAL.A, WEIR and NEATBY (13) agree, at least in part, with SACHS. MASON (12) and Popp and BROWN (16) have stressed the action of ultraviolet rays in checking growth. MASON found that date frond elongation stopped soon after sunrise at Indio, California, and was not resumed until near sunset. Growth was resumed within a few minutes if the plants were covered during the day, but could be stopped under the cover or at night by the radiation of a quartz mercury arc. Tropical workers, BROWN and TRELEASE (2), COSTER (3), OSMASTON (14), PORTERFIELD (17) and TRELEASE (21), are generally agreed that daytime checks of plant growth are caused by internal water deficits in insolated plants rather than by any direct action of light. It might be assumed that the lower percentage of ultraviolet in the sunlight of the humid tropics accounted for their observations if it were not that LLOYD (9) was unable to find any direct effect of sunlight upon the growth of Eriogonum nudum at the Desert Laboratory at Tucson. LOoMIS (11), working with potted maize plants in the greenhouse, concluded that the elongation of this plant was controlled by the temperature and the internal water supply of the plant and was not directly affected by light. Temperature is normally positively correlated with radiation, but water supplies within the meristematic tissues tend to be negatively correlated. The greenhouse glass would reduce the ultraviolet of sunlight by screening out the shorter and more active wavelengths. PRESCOTT (19), however, found that maize in the field in Egypt also made its greatest growth after sunrise in the morning and around sunset, with a midday drop that was accentuated by declining soil moisture percentages. There

Relation between electrical and curvature responses in the avena coleoptile to mechanical stimuli.

Abstract: When an Avena coleoptile is placed in the horizontal position, it grows away from the center of the earth. This bending is the result of unequal rates of elongation of the upper and lower sides of the plant, and is commonly explained on the basis of the familiar Cholodny-Went theory of plant curvature responses (3, 19). The early work of Bose (2) and, in recent years, the experiments of Brauner (4, 5, 6) and Brauner and Amlong (7) have demonstrated that the under side of various plant stems becomes electropositive to the upper side when these stems are placed in the horizontal position. Wilks and Lund (20) have performed preliminary experiments which show that the under side of a horizontally placed Avena coleoptile also becomes positive to the upper side. It has been conclusively confirmed (17), not only that the under side of the coleoptile becomes positive to the upper side, but that the entire internal electrical correlation pattern (12) changes when the position of the living coleoptile is changed from vertical to horizontal. Frequent observations have shown that mechanical stimulation of a segment of living tissue causes that segment to become electronegative to unstimulated regions. This has been proved to be the case for the electrically polar growth axis in the Douglas Fir (13), in the root of Allium cepa (14), and Chara vulgaris (8). Certain observations of Bose (1) and Orbeli and Br?cke (15) might be considered exceptions to this phenomenon. The growth response to mechanical stimulus, which was first studied in tendrils is also rather widely distributed in etiolated seedlings and other stems. Stark (18) was able to induce curvature in the Avena coleoptile and other plants by stroking one side of the plant with a cork rod. The stimulated side became the concave side. More extensive references are cited by Stark. The experiments herein reported are intended to show, in a semi-quantitative way, how mechanical stimulation affects the transverse electrical polarity, the growth curvature, and their sequence relationships in the Avena coleoptile while in the upright and in the horizontal positions.

Relation of the production of an active emanation to respiration in the avocado fruit.

Abstract: The production of physiologically active emanations by plant tissue in general, and especially by ripe fruit, has been demonstrated by epinastic responses of tomato and potato leaves, by inhibition of seed germination and potato sprouting, by the triple response of etiolated legume seedlings, and by effects on fruit respiration and softening. In all cases which subsequently have been investigated chemically, the active substance has been shown to be ethylene. This is now so well established and generally accepted that demonstration of the activity of an emanation by any of the above methods is a very strong indication that ethylene is among the gases evolved [ (18, 19, 20, 21) and review by Biale and Shepherd (4) ]. A number of workers have found that the production of ethylene by various fruits is associated with the increase in rate of carbon dioxide output which is known as the climacteric rise in fruit respiration. Hansen (7, 8) and Hansen and Hartman (9) found that the peak of ethylene production coincided closely with the climacteric peak in the pear. Kidd and West (11) report that the development of the substance in apple vapor which inhibits germination of pea and mustard seeds coincides with the climacteric rise. Nelson (14, 15) found that several varieties of apples show a pattern of varying ethylene content throughout storage life analogous to the course of carbon dioxide evolution. Subsequently (17) he compared the evolution of carbon dioxide and ethylene by the Mclntosh variety. In this study it appeared that the peak of ethylene production occurred somewhat later than the peak of carbon dioxide output. On the other hand, for the banana (14, 15,16) he found that the highest rate of ethylene evolution comes before the peak of carbon dioxide production, with a secondary peak afterward; evidence was presented that ethylene is consumed during the peak of carbon dioxide output. Denny and Miller (6) obtained a positive epinastic response with young potato plants subjected to the emanations of avocado fruit, and recent studies on the respiration of the avocado (2, 3, 22) have shown that this fruit has a well-marked climacteric rise. It therefore became of interest to study the relation between production of active emanations and the course of respiration.

Composition of fruits and phloem exudate of cucurbits.

Abstract: Phloem ex?date has been used in many studies on solute transport in plants As far as can be determined by microscopic observation, it comes from the sieve tubes and represents, therefore, an unmixed sap that moves rapidly within the plant If the ex?date from cut peduncles of cucurbit fruits represents a true sample of a solution of food materials moving through the phloem by mass flow to nourish those fruits, there should exist a fairly constant proportionality between the various compounds present in the ex?date and in the fruits That the process of phloem exudation has been variously interpreted in the past is apparent from the following review of literature Since the researches of H artig and N?geli (6) it has been commonly assumed that the sieve tubes of the phloem tissue of plants are continuous elements interconnected by open pores through which substances in solution may pass more or less freely Phloem exudation from cut cucurbit stems, described in detail by N?geli, was cited as confirming evidence for an open system; and many considered it a manifestation of the normal process of food transport Zacharias and Kraus (6), analyzing such ex?date, showed that it contained sugar, organic nitrogen compounds, potassium, and phosphorus, all of which were presumably translocated in the phloem The works of Fischer, Strasburger, and Hill (6) tended to confirm this early interpretation The cucurbit sieve tube became the accepted type of food-conducting element, illustrated in elementary texts, and often cited as an example of adaptation of structure to function To many botanists the structural aspects of the process of food transport in plants seemed clear In 1855, however, von Mohl questioned the actual perforation of the sieve plate, contending that the middle lamella remained intact Lecomte described the protoplasm as penetrating into the striations of the callose plates in the form of filaments terminating at the swellings in knobs Such structures are commonly found in the position of the middle lamella of the sieve plate The researches of Hill, Strasburger, and other early workers (?) emphasized the extreme fineness of the sieve-tube connections in many plants, the gymnosperms in particular Kuhla (16) denied the perforation of the protoplasmic connection of the sieve plate, and since then others have shared his view (6, 9, 26, 27) If the sieve tubes are not perforate elements through which ready mass flow of solutions can take place, how are foods transported in plants? Birch-Hirschfeld (1), Dixon and Ball (12), and Mason and Lewin (18) concluded that they move through the xylem Later, Dixon (11) and

The growth of chlorella pyrenoidosa under various culture conditions

Abstract: The unicellular algae are being used with increasing frequency in studies on the nature of the photosynthetic mechanism. These algae are excellent experimental material. Their measurable gas exchange is not subject to certain of the complexities of higher plants, e.g., stomatal behavior. They can be used in thick suspensions to obtain almost total light absorption or in such thin suspensions that the variation in light intensity within the sample becomes negligible. They are adapted to the comparatively simple and accurate manometric measurement of gas exchange. Furthermore, effects of individual variation among samples from any one batch of cells are minimized since any one sample usually contains billions of individuals. The procedure of growing algae introduced by Warburg (16) and described in detail by Gaffron (4) has been commonly followed. Certain strains of the alga Chlorella have been most widely used. In one sense the choice of this form is not particularly fortunate since it reproduces by formation of a variable number of autospores within the parent cell. This means that Chlorella cells may be subject to wider variation in size than might be expected of a form such as Stichococcus which multiplies by binary fission. Cultures are commonly grown in a mineral salt solution in 250to S00-ml. flasks, with a current of air fortified with carbon dioxide (^ 3 to 5 per cent.) bubbled through, at a temperature in the range of 20 to 25? C, and illuminated by a tungsten filament lamp giving an incident intensity in the range of 50 to 500 foot candles. This technique has proved so convenient and reliable that no comprehensive study of growth conditions has been undertaken. A few workers have chosen other algae or followed other procedures of culture, but the study of growth conditions or comparison between various algae has been limited. In one sense the standardization of procedure in culture is fortunate since comparisons between data of different laboratories are facilitated. But by the same token the photosynthetic mechanism has been given an appearance of stability which may not be warranted. It would seem that a point has been reached at which the relations between culture conditions and the development of the photosynthetic mechanism can profitably be explored. It is the thesis of this and succeeding papers of the series that one approach to the photosynthesis problem lies in a study of photosynthetic behavior in relation to conditions of culture. A step in this direction has been taken by Sargent (12) in studying certain effects of light intensity on photosynthetic behavior.

The cultivation of chlorella sp

Abstract: The writer became interested in the growth of algae in culture (4, 5, 6, 7, 8, 11, 20, 21, 23, 24, 25) while engaged in attempts to isolate a few of the common species. In particular the relation of these plants to the element calcium was considered. Molisch (15) was the first to report that certain algae can grow normally when calcium is excluded from the media in which they are cultured, while others soon die without this element. Benecke (1) also grew a few species in calcium-free culture solutions, and confirmed the conclusion of Molisch that calcium is not essential for the growth of some algae. In spite of many inoculations with fresh material of Chlamydom?nos ting ens A. Braun, however, Frank (9) did not succeed in growing this alga in calcium-deficient cultures. Richter (22) found that two diatoms, Nitzschia palea (Kuetz.) W. Sm. and Nav?cula min?scula Grun. also could not grow without calcium. Likewise, Maertens (12) proved that this element was indispensable for the bluegreens, Oscillatoria brevis Kuetz. (Oscillarla brevis Kuetz.), 0. tennis Ag.> and Nostoc sp., and that strontium could not be completely substituted for it in cultures of the last two algae (the first was not investigated). Waren (28) reported that, in general, cell divisions were not possible in the desmid Micrasterias rotata (Grev.) Ralfs when there was a deficiency of calcium. That a relationship might exist between the calcium requirements of a plant and its systematic position was suggested by Pringsheim (21). Algae which could grow without calcium were classed with the lower plants such as the fungi, while those which could not grow without it were grouped with the higher plants. He investigated a large number of algae, some of them producing no growth without calcium and others as Chlorella sp. 1 and 2 developing with or without this element. These latter species continued to develop after several transfers from one calcium-deficient solution to another, but notwithstanding the precautions which were taken his results were not always clear. Among other investigators who have cultivated different strains of Chlorella in solutions with a deficiency of calcium are Hopkins and Wann (10), Trelease and Selsam (26), Pratt (16, 17), and Pratt and Fong (18, 19). Their works will be referred to later.

Effects of iron on chlorophyllous pigments, ascorbic acid, acidity and carbohydrates of ananas comosus (l.) merr., supplied with nitrate or ammonium salts.

Abstract: In a former paper (12) data were presented on the effects of iron on growth, certain physiochemical properties, and ash constituents of Ananas comosus (L.) Merr. The present paper is concerned with data from the same plants pertaining to the amounts and distribution of chlorophyll, carotenoid pigments, titrable acidity, ascorbic acid, dextrose, l?vulose, sucrose, starch, the pentosan and hexosan fractions of hemicellulose, cellulose and lignins in different sections of the leaves, stem, and roots.

Effect of boron, copper, manganese, and zinc on the enzyme activity of tomato and alfalfa plants grown in the greenhouse.

Abstract: In recent years much effort has been made to ascertain the necessity of certain so-called minor elements in the economy of plants and animals. It is only recently that attention has been given to physiological aspects of minor-element nutrition. The present investigation was begun to ascertain the effect of copper, boron, manganese, and zinc on enzyme activity in the plant. Catalase, peroxidase, oxidase, and invertase were included in the study. The literature of the effect of minor elements on enzymes in plants is meager. Alexander (1) found that the catalase activity in squash plants was increased by boron deficiency. Haas and Klotz (8) observed a slight increase in diastatic digestion in citrus plants in response to boron deficiency. It has been suggested that manganese may have certain stimulating "catalytic'' functions, such as inactivation of oxidizing enzymes (11, p. 112). Wynd (19) studied the effect of small amounts of iodine on enzymatic activity in tomatoes. Low concentrations of iodine (1 and 5 p.p.m.) decreased invertase, peroxidase, and catalase activity. Higher concentrations (10 and 20 p.p.m.) produced marked increases in these enzymes. Oxidase activity was depressed with all treatments. Peptase gave no response to any of the iodine additions. Methods

Radioautographs showing the distribution of sulphur in wheat.

Abstract: The radioactive elements emit rays which are able to affect the photographic plate and it is possible to determine by contact exposure the approximate concentration-distribution of the element in flat sections of plant or animal material, sometimes locating boundaries within a few microns. These exposures are called radioautographs (or more simply autographs). As the different elements vary over a wide range in regard to the nature and intensity of their radiation, the conditions for proper exposure of the plate vary correspondingly. Hamilton states (7) that bombardment by 2 ? IO6 beta particles of at least 0.15 M.E.V. average energy per sq. cm. plate surface is necessary for production of a satisfactory image. X-ray film gives the most rapid results but if it is necessary to magnify the autograph considerably, the graininess of the film is objectionable and slower; fine-grained film should be used instead if possible. Radioautographs of animal structures have been prepared using phosphorus* (12),2 iodine* (8) and others. Hamilton, Soley, and Eichorn (8) in a study of the iodine* content of goiter tissue, made paraffin sections of the tissue, removed the paraffin, and dipped the sections in a dilute solution of collodion which was allowed to dry. The sections were then placed in contact with the film separated only by a layer of collodion approximately one micron thick. Arnon, Stout, and Sipos (1) and also Colwell (6)3 have investigated translocation in plants, partly by means of autographs using radiophosphorus. The activity of radiophosphorus is so great that it is possible to obtain good autographs through several layers of paper after exposures as short as one hour. Autographs employing sulphur* have not been found in the literature. Sulphur* radiation has only about one-fourteenth the energy of phosphorus* radiation and special precautions are necessary to avoid absorption of the former before it reaches the plate. Particularly, it is necessary to place the film in close contact with the sections, with a minimum of intervening material which might absorb a portion of the emanating rays. This paper completes the observations described in the preceding paper (16) by submitting autographs to show the distribution of the sulphur* in the spring wheat.